Color image pick-up tube having a silicon target plate

ABSTRACT

In a color image pick-up tube using a silicon target plate as a photo-electric transducer, the main portion of the face plate is slightly elevated except at its peripheral annular portion to form a flat-topped convexity on which a color filter is formed and the peripheral protrusion of the silicon target plate is fastened to the peripheral annular portion of the face plate, so that the target area of the target plate is arranged in opposition to the color filter with a small gap left therebetween.

United States Patent 1 1 Matsumulra et al.

[ .lune4, 1974 54] COLOR IMAGE PICK-UP TUBE HAVING A SILICON TARGET PLATE [75] Inventors: Taroemon Matsumura, Suita;

Tadashi Hasegawa, Kyoto, both of Japan [73] Assignee: Matsushita Electronics Corporation,

Osaka, Japan [22] Filed: July 25, 1972 [2]] Appl. No.: 274,932

[30] Foreign Application Priority Data July 28, l97l Japan 46-57055 7 52 us. c1. 313/367 511 11m. (:1. H0 lj 29/36 581 Field 61 Search 313/65 R, 65 A, 65 AB,

[56] References Cited UNITED STATES PATENTS 2.446,79l 8/1948 Schroeder 313/66 Zwicker et al. 313/65 AB Hanaoka et al 3l3/66 Primary Examiner.Herman Karl Saalbach Assistant ExaminerSiegfried H. Grimm Attorney, Agent, or F irm-Ladas, Parry. Von Gehr, Goldsmith & Deschamps [5 7] ABSTRACT In a color image pickup tube using a silicon target plate as a photo-electric transducer, the main portion of the face plate is slightly elevated except at its peripheral annular portion to form a flat-topped convexity on which a colorfilter is formed and the peripheral protrusion of the silicon target plate is fastened to the peripheral annular portion of the face plate, so that the target area of the target plate is arranged in opposition to the color filter with a small gap left therebetween.

4 Claims, 2 Drawing Figures COLOR IMAGE PICK-UP TUBE HAVING A SILICON TARGET PLATE riphery of the face plate so that there is provided a 'small gap between the target area of the target'plate and the color filter..

An image pick-up tube called a "silicon vidicon" which employs a silicon target plate as a photosensitive transducer, has been in current use. Moreover, it is generally known that an ordinary image pick-up tube can be converted to a color image pick-up tube by merely attaching a color filter tothe'face of the ordinary image pick-up tube. In this case, however, there is a gap (equal to the thickness of the glass constituting the face plate of thetube) between the color filter disposed on the outer surface of the face plate and the silicon target provided on the inner surface of the face plate, so that a fiber plate has to be used as such a face plate in order to improve the efficiency of the tube. This adds to the production cost of the tube.

According to the present invention, the inner surface of the face plate is slightly elevated except at its peripheral annular portion so as to form a circular plateau and a color filter is formed on the plateau. Further, the silicon target is fastened at its peripheral protrusion to the peripheral annular portion of the face plate soas to arrange the target area of the target plate in opposition to the color filter and to provide a small gap therebetween.

For a better understanding of the present invention, reference may be had to the attached drawings in which: I I

FIG. 1. is a sectional view of the main portion of a color image pick-up embodying the present invention; and v FIG. '2shows a part of the main portion shown in FIG. I, which isexplained in detail concerning the present invention.

In FIG. I, a face plate 3 is fastened to the open end of a cylindrical glass envelope 1 by means of an indium ring 2 fused to both members. The face plate 3, as seen also in FIG. 2, comprises a peripheral annular portion 4 and a main portion 5 encircled by the annular portion 4. The main portion 5 is slightly convex and its surface is flat. On the flat surface are disposed a color filter 6 constituted of red R, green G and blue B filter segments in the form of stripes which are arranged one after another in this order mentioned with an index line (I) interposed between adjacent stripes. A circular silicon target plate 7, of N-type silicon single crystal comprises a target area 27 having a small thickness, on the surface of which a matrix of p-n junction photosensitive elements 37 is formed and a peripheral portion, i.e., annular protrusion 17. The target plate 7 is mounted on the face plate 3 with its annular protrusion 17 resting on the annular periphery 4 on the face plate. In the preassembly shown in FIG. 2 of the face plate 3 and the target plate 7, the relative position between the p-n junction photosensitive elements 37 of the target area 27'and the stripe segments of the color filter 6 is adjust'ed, and adhesive agent is applied at several portions between the peripheral annular portion 4 and the annular protrusion 17 so as to fasten them together. The control of the relative position can be performed, for example, through the light penetration method so that the photosensitive elements 37 and the segment stripes of the color filter 6 may be brought in registration with each other.

The thickness a of the target area 2.7 of the silicon target plate 7 is preferably set within a range from 15 to 25 microns while the thickness b of the annular protrusion 17 is about 150 microns. The diameter of each of the p-n junction photosensitive elements 37 is about 8 microns and the space between adjacent elements is about 20 microns. The gap C between the color filter 6 and the target area 27 is about 30 microns or less. A perforation may be cut in a portion of the silicon target plate 7, if necessary, which serves as a vent for evacuating gas.

The preassembly of the'face plate 3 and the target plate 7 is then fastened to the glass envelope 1. In this process, a metal ring 10 having a flange ll is disposed on the target plate 7, as seen in FIG. I, with a metal spring 9 interposed between them, and the flange ll of the metal ring 10 is pressed into the indium ring 2 when the indium ring 2 is fused to fasten the face plate 3 and the target plate 7 and rigidly fixed therein. Therefore, the silicon target plate 7 is always urged toward the face plate 3 by the metal spring 9 and the spring 9 keeps an ohmic contact with the target plate 7. The metal spring 9 is electrically connected through the metal ring 10 and the indium ring 2 with the ring shaped electrode terminal 12 disposed outside the glass envelope.

With the construction described above, the silicon target plate 7 and the color filter 6 opposing the target area 27 are both located inside the face plate 3, i.e.,

within the glass envelope 1, and therefore the gap between the two members can be made so small that there can be eliminated a drawback which would be caused with the constitution wherein a fiber plate is used as the face plate3. Further, the silicon target plate 7 is fastened to the face plate 3 at its annular protrusion 17 so that the mechanical strength of such a supporting structure is. very high and that the positioning of the two members can be more accurately done. Moreover, there is provided a small gap between the target area 27 off the silicon target plate 7 and the color filter 6 so that any optical deterioration as well as distortion due to the contact of the target area 27 with the color filter 6 is prevented. This is also one of the merits of the present invention.

What weclaim is:

l. A color image pick-up tube, comprising a cylindrical envelope, a face plate having a peripheral annular portion and a main portion encircled by said annular portion, said annular portion being attached to the open end of the cylindrical envelope to provide hermetic sealing and said main portion being slightly elevated to form a plateau extending inwardly into the envelope, a color filter located on said plateau, and a silicon target plate having a peripheral annular protrusion and a target area encircled thereby having p-n junction photosensitive elements formed in the target area surface, said'target plate being located within the envelope over said inwardly extending plateau and being fastened to said face plate at its annular protrusion, the

4. A color image pickup tube according to claim 1 in which said face plate is attached to the open end of the cylindrical envelope by an indium ring, and a metal ring is provided surrounding the peripheral portion of the target plate and having a flange rigidly held by said indium ring, spring means being located between said metal ring and the peripheral portion of the target plate to urge the target plate towards the face plate.- 

1. A color image pick-up tube, comprising a cylindrical envelope, a face plate having a peripheral annular portion and a main portion encircled by said annular portion, said annular portion being attached to the open end of the cylindrical envelope to provide hermetic sealing and said main portion being slightly elevated to form a plateau extending inwardly into the envelope, a color filter located on said plateau, and a silicon target plate having a peripheral annular protrusion and a target area encircled thereby having p-n junction photosensitive elements formed in the target area surface, said target plate being located within the envelope over said inwardly extending plateau and being fastened to said face plate at its annular protrusion, the size of said protrusion being such that said color filtEr and target plate extend parallel to each other with a small gap there between.
 2. A color image pick-up tube according to claim 1, wherein said color filter is formed of filter segment stripes and the p-n junction photosensitive elements correspond in location to said filter segment stripes.
 3. A color image pick-up tube according to claim 1, wherein said gap between said color filter and said target area is about 30 microns or less.
 4. A color image pick-up tube according to claim 1 in which said face plate is attached to the open end of the cylindrical envelope by an indium ring, and a metal ring is provided surrounding the peripheral portion of the target plate and having a flange rigidly held by said indium ring, spring means being located between said metal ring and the peripheral portion of the target plate to urge the target plate towards the face plate. 